Thermal circuit breaker



Oct. 2l, 1947. s, 5 GRADY ,THERMAL CIRCUIT BREAKER File'd Juiy 31, 1945NTOR . @Wwf lll l.

ATTORNEY Patented Oct. 2l, 1947 UNITED vSTATES" PATENT OFFICE 9 Claims.(Cl. 200-116) This invention relates t circuit breakers in general.

Among the objects of the present invention, it is aimed to provide animproved circuit breaker relying upon a bi-metal deflector sensitive toheat in case of an overload to initiate the break or interruption in thecircuit thereby to afford protection to the apparatus and to avoid wellknown hazards and damage resulting from an overload in a circuit.

It is still another object of the present invention to provide animproved circuit breaker which includes a snap or quick acting switchfor interrupting a current in case of an overload, which switch howevercan quickly be reset after the abnormal .condition has been overcome,ready for another emergency.

The invention still further contemplates an improved circuit breakercomprising a quick acting switch which will instantaneously,interruptthe current when an overload occurs initiated by the deection of abi-metal thermostat and at the same time actuate an insulating shieldinto the gap formed between the main contacts when the interruption iseffected,

These and other features, capabilities and advantages of the inventionwill appear from the subjoined detail description of one specicembodiment thereof illustrated in the accompanying drawings in whichFig. l. is a plan View of a container or panel having mounted therein anumber of circuit breakers made according to the present invention;

Fig. 2 is a section on the line 2-2 of Fig. l;

Fig. 3 is a front elevation of one of the circuit lbreakers as a unitpartly in section and slightly enlarged as to the scale of Fig. l;

Fig. 4 is a rear elevation of the unit shown in Fig. 3 partly insection;

Fig, 5 is a section on the line 5--5 of Fig. 3;

Fig. 6 is a front elevation of the unit with the circuit breaker incircuit interrupting position;

Fig. 7 is a front elevation of a unit after an overload has actuated theswitch to interrupt the circuit;

Fig. 8 is a section on the line 8-8 of Fig. 3.

In the present embodiment, there is provided an insulating block havinga base l and an upright 2. Secured to the'lower face of the base I`largement Ii on the arm 5.

there is 'provided a bracket 3 having an arm 4, Figs. 3 and 8,constituting one terminal of the switch or circuit breaker. The bracket3 also has an upright 5 provided with an enlargement 6 to constitute thexed contact of the circuit breaker. To the lower face of the base Ithere is also secured the bracket 'I having the arm 8, Figs. 4 and 8,constituting the other terminal of the circuit breaker. The bracket 'Ihas upwardly extending therefrom the bi-metal thermostat 9 which isconnected by the flexible conductor I0 to the centrally disposedsupporting plate II, the flexible conductor IIJ being connected to thearm I2 of the plate I I. The plate I I is secured by the flange I I0 tothe upper face of the base I, see Fig. 5. The plate II has an abutmentI3 formed thereon to which there is secured a coil of the wire springI4, one end of which, to wit the end I5, is preferably secured in thebase I and the arm I6 of which spring I4 has a linger II to engage theshoulder I8 on the steel section I9 of the bi-metal thermostat 9. Thearm I6 has an elbow 20 and adjacent to same a cam face 2I to cooperatewith the shoulder 22 on the blade 23 pivoted at 24 to the plate Iladjacent to the base I, The blade 23, see Fig. 5, has a cross-piece 25and an extension 26 extending down one face of the plate II while themain part of the blade 23 extending up from the pivot kpin 2-4 extendsalong the other face of the plate Il. The extension 26 has a projection21 to which is connected one end of the spring 28, the other end ofwhich is connected to the pin 29 adjacent to the free end rof theL-shaped lever 30. The pin 29 in the present instance is disposedsubstantially at the intersection of the arms 3l and 32 of the lever 30.The lever 30 is pivotally connected by the pin 33 to the plate II. Thearm 32 preferably has an enlargement 34 at the end thereof constitutingthe contact element to engage the contact en- The spring 28 willcooperate with the blade 23 and arm 3| to form a snap or toggle switch,the spring being disposed to one side of the pivot pin 33 of the arm 30in contact making position and to the other side of the pivot pin 33 incontact breaking or open position of the circuit.

The upright 2 has a slot therein to receive the insulating gate 35 whichin lowered position, that shown in Fig, 6, cooperates with the flange 36effectively to close the gap between the contact 6 and the contact 34.The gate 35 has an opening |36 therein to receive the finger orprojection 31 formed on and extending from the upper end oi the arm 3|of the plate 30. The plate or lever Si) also has a resetting finger 38,Figs. 3, 4, 6 and '1, extending at right angles to the main part of theplate 30 and into the area above the finger I1 and to one side of theelbow 20 of the arm I6.

Preferably the plate II, see Fig. 4, has two extensions 39 and 48. Theextension 40 may serve as a limiting stop for the blade 23, see theposition of the extension 28 of the blade 23, in engagement with theshoulder 40 in Fig. 4, in contactl making position when the springfinger I1 engages the shoulder I8 of the bi-metal thermostat fi. In suchposition, the finger 4I on the lower end of the blade 23 adjacent itspivot pin 24 may also engage the upper edge of the arm 32 of the lever3B, see Figs. 3 and 4. The eXtension 39, on the other hand, may serve asa limiting stop for the plate 23 in circuit breaking position.

In operation, to set the finger I1 it is only necessary to move theblade 23 from the position in Fig. '1 into position shown where theelbow 2Q will engage the cam face 22 and depress the iinger I1 intoengagement with the shoulder I8, see Fig. 6. Thereupon the blade 23 maybe swung back into the position shown in Fig. 3, when due to the actionof the spring 28, the contact 34 is brought into engagement with thecontact 6. At the same time, the spring 28 will cause the lever 3Uthrough its finger 31 to raise the gate 35 into the position shown inFig. 3 where the gap will be formed and the arm 32 will extend under thegate 35 and over the shoulder 36 to enable its contact 34 to engage thecontact 6.

In the position illustrated in Fig. 3, the circuit breaker is ready foroperation. Should an overload arise and the overload continue longenough to affect the thermostat 9 to deiiect it, it will release thefinger I1 due to the spring tension in the spring arm I6, cause thefinger I1 to rise or snap upward to engage the finger 38 and thrust itupward in turn to rock the lever 30 to swing the spring 28 into positionwhere it will withdraw its arm 32 out of the gap beneath the gate 35, atthe same time withdraw the contact 34 from the contact 6, and at thesame time cause the finger 31 to lower the gate 35 into gap closingposition.

If the abnormal condition ceases and it is desired again to close thecircuit, it is only necessary to swing the blade 23 back into theposition shown in Fig. 6 where it will reset the nger I1 in engagementwith the shoulder I8, whereupon the blade 23 may be swung over intoposition where it will cause the Contact 34 to engage the contact 6 andraise the gate 35 out of the gap between the contacts 34 and 6. Innormal contact making position, when the finger I1 engages the shoulderI8, the current will pass from the bracket 3 to the contact 6 and fromthe contact 6 to the contact 34 and then through the lever 38 to itspivot pin 33 and from its pivot pin 33 through the plate II to thefiexible conductor I0, from the fiexible conductor I to the thermostat 9and from the thermostat 9 to the bracket 1.

Preferably to facilitate actuating the blade 23, the upper end of theplate 23 is provided with an insulating finger piece 42. The cross-piece25 of the blade 23 in turn is positioned to move across the insulatingstrip 43 secured to the extensions 39 and 40 on the plate I I.

Preferably, especially when the circuit breakers are mounted in a boxwith other circuit breakers, an insulated housing is provided having twoside walls 44 and 45 connected to the end wall 48 which are secured tothe base I and have an arcuate top wall 41 provided with a slot 48 toclear the neck 49 of the finger piece 42. The end wall 46 is disposedadjacent the thermostat 9. The other end wall 50 extends down from thearcuate wall 41 to the contact 6, see Fig. 3. The circuit breakers sohoused, see Figs. 1 and 2, are then mounted upon the base 5I of thepanel which is provided with side walls 52 and 53 and a cover 54 havingopenings therein to clear the upper portions of the individual circuitbreaker housings 55 and 56 as shown in Fig. 2.

In the present instance, adjacent to the thermostat blade 9, there isprovided the extension or upright 51, preferably integral with thebase 1. The thermostat 9 is so constructed that when it is heated due toan overload, it will deflect toward the extension or upright 51. If theheat is sufficient to cause the blade 9 to deflect far enough, in turnto cause its upper edge to engage the extension 51, then the currentwill be shunted to pass from the conductor I0 through the upper edge ofthe blade 9 to the extension 51 and thereby relieve the blade 9 in turnto prevent it from being overheated.

Obviously, the bi-metal thermostat 9 may be made of any of the twodifferent metals conventionally used instead of copper and steel.

It is obvious that various changes and modifications may be made to thedetails of construction without departing from the general spirit of theinvention as set forth in the appended claims.

I claim:

1. The combination of a fixed contact, a pivotally mounted plate havinga movable contact for engagement with said fixed Contact, a springcontrolled blade forming a toggle with said plate for actuating saidplate into circuit making and circuit breaking position, a finger onsaid plate, a spring actuator for engaging said finger and rocking saidplate into circuit breaking position,

and a bi-metal thermostat normally anchoring said spring actuator out ofengagement with said finger, said thermostat being connected to thecircuit under control and sensitive to an overload to free said springactuator and allow said spring actuator to actuate said finger in turnto withdraw the movable contact out of engagement with said fixedcontact.

2. The combination of a fixed contact, a pivotally mounted plate havinga movable contact for engagement with said fixed contact, a springcontrolled blade forming a toggle with said plate for actuating saidplate into circuit making and circuit breaking position, a finger onsaid plate, a spring actuator for engaging said finger and rocking saidplate into circuit breaking position, a bi-metal thermostat normallyanchoring said spring actuator out of engagement with said finger, saidthermostat being connected to the circuit under control and sensitive toan overload to free said spring actuator and allow said spring actuatorto actuate said finger in turn to withdraw the movable Contact out ofengagement with said fixed contact, and a handle operatively connectedto said toggle to actuate said plate and movable contact into and out ofcircuit making position.

3. The combination of a fixed contact, a pivotally mounted plate havinga movable contact for engagement with said fixed contact, a springcontrolled blade forming a toggle with said plate for actuating saidplate into circuit making and circuit breaking position, a finger onsaid plate, a spring actuator for engaging said finger and rocking saidplate into circuit breaking position, a bi-metal thermostat normallyanchoring said spring actuator out of engagement with said finger, saidthermostat being connected' to the circuit under control and sensitiveto an overload to free said spring actuator and allow said springactuator to actuate said finger in turn to withdraw the movable contactout of engagement with said fixed contact, said blade including ashoulder, and a handle connected to said blade for actuating said bladeinto circuit breaking position to enable said shoulder to reset saidspring actuator into anchoring engagement with said thermostat.

4. The combination of a fixed contact, a pivotally mounted plate havinga movable contact for engagement with said fixed contact, a pivotallymounted blade, a spring operatively connecting said plate and blade toform a quick acting toggle to actuate said movable contact into or outof circuit making position, a finger on said plate, a spring actuator, athermostat in the electric circuit normally anchoring said springactuator, said thermostat being deflected in case of an overload to freethe spring actuator and enable it to actuate said finger in turn toactuate said plate into circuit breaking position, and a shoulder onsaid blade cooperating with said spring actuator to reset it intoanchoring engagement with said thermostat upon actuation of said blade.

5. The combination of a fiXed contact, a Divotally mounted plate havinga movable contact for engagement with said fixed contact, a springcontrolled blade forming a toggle with said plate for actuating saidplate into circuit making and circuit breaking position, a first fingeron said plate, a spring actuator for engaging said first finger androcking said plate into circuit breaking position, a bi-metal thermostatnormally anchoring said spring actuator out of engagement with saidfirst finger, said thermostat being connected to the circuit undercontrol and sensitive to an overload to free said spring actuator andallow said spring actuator to actuate said finger in turn to withdrawthe movable contact out of engagement with said fixed contact, aninsulating gate slidably mounted between said xed contact and saidmovable contact, and a second finger integral with said plate engagingsaid gate upon the actuation of said plate to move said gate intoposition between said fixed contact and movable contact in circuitbreaking position and to clear the gap between such contacts in circuitmaking position.

6. The combination of an insulated housing, a fixed contact for anelectric circuit formed on the outside of said housing, a bearing platedisposed inside of said housing, a second plate pivotally mounted onsaid bearing plate and having a movable contact actuatable to extendfrom said housing into engagement with said fixed contact in circuitmaking position, a blade pivotally connested to said bearing plate, aspring operatively connecting said blade and said second plate to form aquick acting toggle to actuate said movable contact into or out ofcircuit making position, a thermostat in the circuit, conductivelyconnected to said movable contact, a spring actuator normally anchoredby said thermostat, a finger on said second plate, and a shoulder onsaid blade in position to actuate said spring active to an overload todeflect and thereby to free said spring actuator and allow said springactuator to actuate said finger in turn to withdraw the movable contactouty of engagement with said fixed contact.

7. The combination of a fixed contact for an electric circuit, a bearingplate, a second plate pivotally mounted on said bearing plate and havinga movable contact for engagement with said fixed Contact in circuitmaking position, a blade pivotally connected to said bearing plate, aspring operatively connecting said blade and said second plate to form aquick acting toggle to actuate said 'movable contact into or out ofcircuit making position, a thermostat conductively connected to saidbearing plate, a spring actuator normally anchored by said thermostat, afinger on said second plate, and a shoulder on said blade in position toactuate said spring actuator to reset the same in anchoring relationwith said thermostat, said thermostat being sensitive to an overload todeflect and thereby to free said spring actuator and allow said springactuator to actuate said finger in turn to withdraw the movable contactout of engagement with said fixed contact.

8. The combination of an insulated housing, a fixed contact for anelectric circuit disposed on the outside of said housing, a bearingplate on the inside of said housing, a second plate pivotally mounted onsaid bearing plate and having a movable contact actuatable to extendfrom said housing into engagement with said fixed contact in circuitmaking position, a blade pivotally connected to said bearing plate, aspring operatively connecting said blade and said second plate to form aquick acting toggle to actuate said movable contact into or out ofcircuit making position, a bi-metal thermostat conductively connected tosaid bearing plate, a shoulder on said thermostat, a spring actuatornormally engaging said shoulder and anchored thereby, a rst finger onsaid second plate, and a cam shoulder on said blade in position toactuate said spring actuator to reset the same in anchoring relation,said thermostat being sensitive to an overload to defiect and in turnfree said spring actuator from said shoulder, and allow said springactuator to actuate said first finger in turn to withdraw the movablecontact out of engagement with said fixed contact an insulating gateslidably mounted between said xed contact and said movable contact, anda second finger on said plate in engagement with said gate upon theactuation of said plate to move said gate into position between saidfixed contact and movable contact in circuit breaking position and toclear the gap between said contacts in circuit making position.

9. The combination of a fixed contact, a pivotally mounted plate havinga movable contact for engagement with said fixed contact to close anelectric circuit, a pivotally mounted blade, a spring operativelyconnecting said plate and blade to form a quick acting toggle toiactuatesaid movable contact into or out of circuit making position, a firstfinger on said plate, a spring actuator, a thermostat in the electriccircuit normally Yanchoring said spring actuator, said thermostat beingdeflected in case of an overload to free the spring actuator and enableit to actuate said rst finger in turn to actuate said plate into circuitbreaking position; a shoulder on said blade cooperating with said springactuator to reset it into anchoring engagement with said thermostatREFERENCES CITED The following references are of record in the file ofthis patent:

Number Number UNITED STATES PATENTS Name Date Grady July 20, 1943 TaylorMay 16, 1939 Guett July 17, 1934 FOREIGN PATENTS Country Date GreatBritain 1914

